Layout refactoring

[noirbizarre]

This PR makes geozones a package and expose geozones cli through setuptools. This allows a clearer separation of concerns and readability (subjective opinion, I agree):

• allows countries as package (ie. geozones.france contains everything related to France including geozones.france.histo)
• only keeps common features and tools on geozones root package
• avoid global imports like import geojson which is also a python package

geo.py has been migrated to geozones/model.py and geozones.py to geozones/__main__.py for coherence.

The new layout is

├── data
│   └── db
├── downloads
├── geozones
│   ├── __init__.py
│   ├── __main__.py
│   ├── dbpedia.py
│   ├── db.py
│   ├── explore.py
│   ├── france
│   │   ├── histo.py
│   │   └── __init__.py
│   ├── geojson.py
│   ├── international.py
│   ├── model.py
│   ├── static
│   │   ├── css
│   │   ├── fonts
│   │   ├── images
│   │   └── js
│   ├── templates
│   │   └── explore.html
│   ├── tools.py
│   └── translations
│       ├── fr
│       │   └── LC_MESSAGES
│       │       └── geozones.po
│       └── geozones.pot
├── babel.cfg
├── docker-compose.yml
├── LISEZMOI.md
├── README.md
└── setup.py

Documentation has been updated accordingly.